Electrical apparatus



J. W. JACOBS ELECTRICAL APPARATUSv Filed Aug. l2, 1952 ,M l 95gO 23 322.' 26 i so 5 J 96..: 28 L Il", 62 o '|39 94 64 LIU- |85 |49 56 76 |49-wlw. 58 86 8 l l Ni l r mi 88 88 |50- '5| 'L35 |43 |5l A 'A M -Memwll MJNVENTOR James W. Jacabs 24242;, zum, nam.

United States Patent O ELEc'rRIoAL APPARATUS James W. Jacobs, Dayton,Ohio, assignor to General Motors Corporation, Dayton, Ohio, acorporation of Delaware Application August 12, 1952, Serial No. 303,977

4 Claims. (Ci. 20G- 83) This invention relates to an electricalapparatus and more particularly to switches and controls.

Experience has shown that the life of the bellows or diaphragm isgreatly reduced in controls wherein the switch mechanism is directlyconnected to the actuated bellows or diaphragm, and a high forcesnap-action toggle mechanism is directly applied to the connection toprovide a wide differential. l have found that the shock and vibrationupon the bellows or diaphragm is so great as to set up a shock wavecausing a whole series of vibrations.

1t is an object of my invention to so arrange such a switch that thelife of its bellows is increased and the shock on the bellows is greatlyreduced.

Itis another object of my invention to so arrange such a switch that thebellows is isolated from the shock taking place in the switch.

It is another object of my invention to so arrange such a switch that alost motion connection connects the bellows and the switch contactmechanism to reduce the transmission of shock and vibration and yetprovide an accurate relationship between the pressure in the bellows andthe operation of the switch contact mechanism.

These objects are attained by this invention, one form of which isdisclosed herein. In the form disclosed, an adjustably mounted bellowsand a switch contact mechanism are mounted within a frame. A memberconnected 'to Vthe switch contact mechanism has the adjacent ends of twotoggle blades pivotally connected thereto. These blades are columnloaded by a folded over leaf spring. An adjustable stop associated withthe member connected to the switch mechanism locates the open positionof the switch while a rotatable cam stops the connecting member invarious positions to locate the closed position of the switch contactmechanism and the toggle blades. To prevent the transmission of shock tothe bellows when the toggle mechanism forces the connection against astop in either direction there is provided a lost motion connectionbetween the bellows follower and the connecting member.

Further objects and advantages of the present invention will be apparentfrom the following description, reference being had to the accompanyingdrawings wherein a preferred form of the invention is clearly shown.

In the drawing: n

Figure 1 is a View partly in section taken substantially along the line1-1 of Figure 2;

Figure 2 is a sectional View taken substantially along the line 2 2 ofFigure 1;

Figure 3 is a fragmentary view similar to a portion of Figure 1 showingthe start of the opening movement of the switch mechanism with thebellows pulling down;

Figure 4 is a fragmentary view somewhat similar to Figure 3 with thetoggle mechanism shown in its position at the end of the openingmovement of the switch Contact mechanism and with the bellows pullingdown; and

Figure 5 is a view similar to Figures 3 and 4 with the parts shown inthe position they assume during the middle of the switch closingmovement with the bellows pushing pReferring now to the drawings andmore particularly to Figure 1 for a disclosure of one form of myinvention, there is shown a U-shaped metal frame 20 having a switchcontact and terminal member 22 of electrical insulating material locatedbetween and connected by the ICC screws 23 to the two legs of the frame.Extending through the terminal member 22 are two terminal posts 24 and26. The inner end of the terminal post 26 has connected to it a thinbent leaf spring contact carrying member 28 having a movement contact 3)fastened to its free end. The adjustable terminal post 24 carries thestationary contact 32.

The operating connection with the contacting carrying member 28 is madeby a member 50 of some suitable electrical insulating material. Thismember 50 has a slot 52 which engages the opposite sides of the member28 as shown in Figure 2. Alongside of the lower portion of the member S0is a connecting member 48 of metal. This metal member 48 on its oppositefaces is provided with sets of notches which receive the adjacentchisel-shaped ends of the toggle blades or links 56 and 5S. The oppositechisel-shaped end of the toggle `clade 58 rests in a notch in a bearingmember 60. This bearing member 66 is rotatably mounted within the innerend of an adjusting screw 62 threaded through the leg of the frame 29.The opposite chisel-shaped end of the toggle blade 56 rests within anotch in a folded over leaf spring 64 having its folded over portionprovided with a pad 76 resting against the adjacent portion of the U-shaped frame 20.

The lower end of this spring 64 is provided with a threaded bushing 67.A screw 7i) threads through the bottom portion of the U-shaped framemember 20 into the threaded bushing. A compression type coil spring 72extends between the bottom of the frame 20 and a shoulder upon the lowerend of the spring 64. This coil spring 72 tends to urge the leaf spring64 upwardly while the screw '70 limits this upward movement and thusadjusts the vertical position of the spring 64. The vertical position ofthe spring 64 adjusts the angularity of the toggle blade 56. The columnloading of the toggle blades 56 and 58 is determined by the adjustmentof the screw 62 which determines the force which will be applied by thespring 64 to the toggle blades 56 and 58. This determines the pressureor temperature difference between the opening and closing of the switchcontacts.

The switch opening movement of the contacts 30 and 32 is limited by alarge flat headed adjustable screw 94 which is threaded into the boss 95extending downwardly from the terminal member 22. The head of this screw94 is engaged by a projection 96 extending from the member 48 beneaththe head of the screw 94.

The member 48 has a cutout portion providing connecting legs and 151.These connecting legs 150 and 151 extend on opposite sides of a camshaft88 which is rotatably mounted in the sides of the U-shaped frame 20.These legs 15) and 151 connect directly with the horizonal yoke 153, aportion of which serves as a follower for the cam 86 which is fastenedto the camshaft 88. The cam S6 has its periphery arranged in the shapeof a spiral with a large nose 87 extending from the periphery betweenthe beginning and the end of the spiral. The camshaft 88 may be rotatedto various angular positions to present different positions of itsperiphery to the yoke 153 for serving as an adjustable stop todeterymine the location of the members 48 and Si) when the contacts 30and 32 are in engagement. This determines the switch opening temperatureor pressure.

When a wide differential is desired between the opening and closingpoint of the switch, the column loading upon the toggle blades 50 and 58is quite high. This causes a considerable shock when the projection 96engages the head of the screw 94 and likewise there is a considerableshock when the yoke portion 153 engages the periphery of the cam 86. ltwas found when the actuating bellows or diaphragm was connected directlyto the yoke 153 that a severe shock was transmitted to the actuatingbellows oh diaphragm. This caused the bellows or diaphragm to set up awave which generates a number of vibrations in the bellows or diaphragm.Since the bellows or diaphragm must be made of spring material which isrelatively hard they are subject to fatigue breakage. These vibrationsgreatly increased the number of exings of the bellows or diaphragm foreach opening and closing of the switch mechanism. This made the life ofthe bellows or diaphragm very short when a wide differential wasrequired.

As shown in Figure 1 in the lower portion of the frame is a flexiblemetal actuating bellows 38. The lower end of this bellows is connectedto a capillary tube 40 which may extend to a source of varying fluidpressure such as a thermostatic bulb. Rotatably mounted upon thecapillary tube 40 is a hollow screw 92 which threaded into the yokeportion of the frame 20. By rotating this screw 92 the lower end of thebellows 38 may be raised or lowered. This changes both the opening andclosing temperatures of the switch.

Instead of directly connecting the bellows 38 to the yoke 153, I providea separate bellows follower 139. This bellows follower 139 has a pair offeet 141 fastened to the top of the bellows 38. One of the feet isprovided with an upwardly extending projection 143 extending through anaperture in the yoke 153. The follower 139 is also provided with a lostmotion slot 145. (See Figure 3) extending through this slot 145 is arivet 149. The shank of this rivet 149 has a large diameter portion inthe slot 145 and a smaller diameter portion extending through aperturesin the members 48 and 50. The members 48 and 50 are tightly clampedbetween the rivet head and the shoulder formed by the larger diametershank portion of the rivet while the opposite end of the rivet islikewise formed with a head to hold the follower 139 in slidingengagement with the adjacent side of the connecting member 48. Thisslidable lost motion connection is therefore made by the rivet 149 withthe lower end of the sliding connection being guided by the slidingprojection 143 upon the member 139 which extends through a slot in theyoke portion 153 at the bottom of the member 48.

Figure l shows the switch mechanism immediately after the bellows 38 hasmoved the switch contact mechanism 28 to the closed position. The yoke153 rests against the periphery of the cam 86. The rivet 149 is in themiddle of the slot 145 so that when the yoke engaged the cam 86 thebellows 38 was disconnected from the member 48 so that no shock could betransmitted to the bellows 38.

To move the switch mechanism 28 to the open position, the pressurewithin the bellows 3S is lowered and when the bellows 38 is collapsedsuiciently the upper end of the slot 145 will engage the rivet 149 tomove the members 48, 50 and 28 downwardly. This movement takes placerapidly with the toggle blades 56 and 58 providing a snap-actionmovement to minimize arcing of the contacts 30 and 32. The toggle blades56 and 58 are approximately in the dead center position in Figure 3.

As soon as the blades pass the dead center position they, along with themembers 48, 5l) and 28, will snap to their lowermost position with theprojection 96 engaging the head of the screw 94 as shown in Figure 4. Inthis movement the rivet 149 will move away from the upper end of theslot to the middle portion where it is shown in Figure 4 as theprojection 96 engages the head of the screw 94. Therefore, when thisengagement takes place the bellows 38 and its follower 139 will bedisconnected from the members 48 and 50 to which the shock is applied.Since the bellows 38 is disconnected from the member 48 when the shockoccurs, the bellows does not receive the shock and does not receive thesevere vibrations lwhich followed the shock when the bellows wasdirectly connected to the toggle mechanism. In this way the life of thebellows was increased more than 100 times.

The return or closing movement of the bellows is shown in Figure 5. Thebellows 38 and its follower 139 move upwardly until the bottom of theslot 145 engages the rivet 149. Further upward movement moves themembers 48, 50 and 28 as well as the toggle blades 56 and 58 until thetoggle blades 56 and 58 cross the dead center position as shown inFigure 5. From this point the toggle blades 56 and 58 as well as themembers 48, 50 and 28 move directly to the position shown in Figure lwithout further movement of the bellows 38. During this latter movementthe rivet 149 moves away from the end of the slot to the position shownin Figure 1 so that at the time of the shock when the yoke 153 strikesthe periphery of the cam 86, the bellows 38 is disconnected and does notsuffer the shock.

In this arrangement therefore the bellows is protected from shockcreated when a high force toggle snapaction mechanism is used to achievea wide diferential.

While the form of embodiment of the invention as herein disclosedconstitutes a preferred form, it is to be understood that other formsmight be adopted as may come within the scope of the claims whichfollow.

What is claimed is as follows:

l. A control including an actuating diaphragm means, a control devicemovable to and from a control position, a toggle snap-action devicedirectly connected to the control device for causing the control deviceto move with a snap action, a stop arrangement for limiting the movementof the control device, and a freely movable limited lost motionconnection connecting said diaphragm means and said control device, saidstop arrangement including a rotatable cam shaft provided with a rotarycam, said control device having a stop portion extending intocooperating relationship with said rotary cam for limiting the movementof the control device in one direction.

2. A control including an actuating diaphragm means, a control devicemovable to and from a control position, a toggle snap-action devicedirectly connected to the control device for causing the controldeviceto move with a snap action, a stop arrangement for limiting themovement of the control device, and a freely movable limited lost motionconnection connecting said diaphragm means and said control device, saidstop ar rangement including a rotatable cam shaft provided with a rotarycam, said control device having a portion extending around the cam andhaving a stop portion on one side extending into cooperatingrelationship with said rotary cam for limiting the movement of thecontrol device in one direction.

3. A control including a control device movable to and from a controlposition, an actuating diaphragm means having an axis along which itsprincipal Vmovement takes place, a follower extending along said axisconnected to a movable portion of said diaphragm means, a connectorextending along said axis in sliding engagement with said follower andconnected to said control device, toggle means connected directly tosaid connector, adjustable stop means for limiting the movement of saidconnector along said axis in either direction, and a pin and slot typelost motion connection between said connector and said follower.

4. A control including a control device movable to and from a controlposition, an actuating diaphragm means having an axis along which itsprincipal movement takes place, a follower extending along said axisconnected to a movable portion of said diaphragm means, a connectorextending along said axis in sliding engagement with said follower andconnected to said control device, toggle means connected directly tosaid connector, adjustable stop means for limiting the movement of saidconnector along said axis in either direction, and a pin and slot typelost motion connection between said connector and said follower, and asliding bearing between said connector and said follower spaced fromsaid lost motion connection.

References Cited in the file of this patent UNITED STATES PATENTS Number

